Questions tagged [integer]
For challenges involving the manipulation of integers.
401
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Find the nth Fibonacci number, where n is the mth Fibonacci number
Introduction
If fib(x) calculates the xth Fibonacci number, write a program that calculates ...
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Spell out an integer... in NDos' way
Objective
Given a positive integer, spell it out in the conlang I made.
Specification
Let \$n\$ be the inputted integer. \$n\$ shall be spelled out in the following specification. The entire spelling ...
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6
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Is it 1089-able?
\$ 1089 \$ is a very special number. To prove why, select any 3-digit number whose first and last digits differ by at least 2. Then, reverse the digits, and take the difference of these two numbers. ...
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14
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The interstice of two binary numbers
Given two integers, compute the two numbers that come from the blending the bits of the binary numbers of equal length(same number of digits, a number with less digits has zeros added), one after the ...
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Randomly Rounding
Input a decimal number and round it to an integer, randomly rounding up or down with a probability based on its fractional part, so the expected value of the output equals to the input value.
If ...
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Double bit rotation to the right [closed]
Given a positive integer as input, output that integer, but with its bits rotated two times to the right. Also, think of the number as a donut of bits, eg. ...
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3
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Line Islands in a Word Search
My third word search related challenge in a row. :)
Challenge:
Brief explanation of what a word search is:
In a word search you'll be given a grid of letters and a list of words. The idea is to cross ...
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Find All Digitroot Cyclic Sequences With Length Greater Than One
Digital sum, DR, Digit root is the iterative process of summing digits of a number until you end up with a single digit root number: e.g. digit root of 12345 is 6 since 1 + 2 + 3 + 4 + 5 = 15 = 1+5. ...
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How-many-bonacci-like is this sequence?
Inspired by @emanresu A's Is it a fibonacci-like sequence? Make sure to upvote that challenge as well!
We say a sequence is Fibonacci-like, if, starting from the third term (\$1\$-indexed), each term ...
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10
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Coordinates for a Heronian tetrahedron
Did you know that Heronian Tetrahedra Are Lattice Tetrahedra? A Heronian tetrahedron is a tetrahedron where
the length of each edge is an integer,
the area of each face is an integer, and
the volume ...
- 8,097
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26
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Sum of the first n elements of the sequence of 9's complement
Let's consider the following sequence:
$$9,8,7,6,5,4,3,2,1,0,89,88,87,86,85,84,83,82,81,80,79,78,77,76,75,74,73,72,71...$$
This is the sequence of \$9\$'s complement of a number: that is, \$ a(x) = 10^...
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How many blocks make a "truncated square-pyramid garden"?
A truncated square-pyramid of height \$h\$ has \$h\$ square layers where each layer has a side \$1\$ greater than the one above it, apart from the top layer which is a square of blocks with a given ...
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Is it a fibonacci-like sequence?
The Fibonacci Sequence is a sequence of positive integers where the first two elements are 1 and the rest are the sum of the previous two. It begins \$1, 1, 2, 3, 5, 8, 13\$ and continues forever.
But ...
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Is given number a concat of two squares
Given a positive integer, determine if it can be represented as a concatenation of two square numbers. Concatenated numbers may not begin with 0 (except for 0). Any leading zeros in input should be ...
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Prime a*b+c of N
Given an integer \$N\$, print or return integers \$a\$, \$b\$, and \$c\$ that satisfy all of the following conditions, if such integers exist:
\$a \times b + c = N\$
\$a\$, \$b\$, and \$c\$ are all ...
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Represent any integer with an expression that uses no digit besides '4' [closed]
Fourward (Introduction)
I have an unhealthy obsession with the number 4. I love it so much, in fact, that seeing any other digit is frustrating to me. I therefour wish to create a 'Fourier ...
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Mirror an integer... in NDos' way
NDos' Numeral System
NDos' numeral system is a numeral system invented by me. It represents every nonnegative integer by a binary tree. Given a nonnegative integer \$n\$:
If \$n=0\$, it is ...
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15
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Encode integers with some others
Input a non-empty array of positive (greater than 0) integers. Output another non-empty array of positive integers which encode the input array. Output array does not use any numbers used in the input ...
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Even sum subarrays
Given an array of integers, count the number of contiguous subarrays with an even sum. You may assume that the array is non-empty, and contains only non-negative integers.
This is code-golf, so the ...
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Is it an elementary matrix?
Consider a linear system of equations, in \$n\$ unknowns, expressed as
$$A \textbf x = \textbf b$$
where \$A \in M_{n,n}(\mathbb Z)\$ is an \$n \times n\$ matrix of integers, \$\textbf x\$ is a column ...
- 46.9k
13
votes
9
answers
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Bijective meets mixed base
Background
A bijective base \$b\$ numeration, where \$b\$ is a positive integer, is a bijective positional notation that makes use of \$b\$ symbols with associated values of \$1,2,\cdots,b\$.
...
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10
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Branchless (MIPS) assembly code for median of 3
I was trying to write a short MIPS32 code for computing the median of three registers.
The rules:
Assume that some values are pre-loaded into $t0, ...
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Nega-Zeckendorf representation
Background
Zeckendorf representation is a numeral system where each digit has the value of Fibonacci numbers (1, 2, 3, 5, 8, 13, ...) and no two consecutive digits can be 1.
Nega-Zeckendorf ...
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18
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Double trace of a square matrix
Inspired by a question (now closed) at Stack Overflow.
Given a square matrix, let its double trace be defined as the sum of the entries from its main diagonal and its anti-diagonal. These are marked ...
- 99.4k
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Self-referential triangle sequence
Output the flattened version of the sequence A297359, which starts like the following:
...
- 62.1k
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Swap Two Values in a List
Introduction:
Although we have a lot of challenges where swapping two items in a list is a subtask, like Single swaps of an array; Swap to Sort an Array; \$n\$ swaps into a nop; etc., we don't have ...
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7
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Maybe fractal sequence?
Background
A fractal sequence (Wikipedia; MathWorld) is an infinite sequence of positive integers meeting the following conditions:
Each positive integer appears infinitely many times in the sequence....
- 62.1k
20
votes
12
answers
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Minimally prepend numbers to get a symmetric Young diagram
Background
A Young diagram is a diagram that represents a nonincreasing sequence of positive integers using left-justified rows of squares. As an example, 5, 4, 1 ...
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25
votes
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"-rot" transform
Background
-rot transform (read as "minus-rot transform") is a sequence transformation I just invented. This transform is done by viewing the sequence as a stack in Forth or Factor (first ...
- 62.1k
12
votes
8
answers
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Boustrophedon transform
Related: Boustrophedonise, Output the Euler Numbers (Maybe a new golfing opportunity?)
Background
Boustrophedon transform (OEIS Wiki) is a kind of transformation on integer sequences. Given a sequence ...
- 62.1k
18
votes
4
answers
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Calculate the integer square root of a matrix
Let \$A\$ be a square matrix that is at least \$2 \times 2\$ where each element is an integer. \$A^2 = A \times A\$ will then have the same dimensions as \$A\$, and will have integer elements. For ...
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5
votes
5
answers
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Potential nonzero entries in an irregular sequence
Background
A338268 is a sequence related to a challenge by Peter Kagey. It defines a two-parameter function \$T(n,k)\$, which counts the number of integer sequences \$b_1, \cdots, b_t\$ where \$b_1 + \...
- 62.1k
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Compare positions of integers in this sequence
A001057 is one way to represent an integer as a natural number. It lists them according to the following pattern:
0, 1, -1, 2, -2, 3, -3, 4, -4, ...
In this ...
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Make an array of random 128 bit integers
Given an input value \$n\$, construct an array of \$n\$ random 128 bit (unsigned) integers. The integers should be uniformly random.
Your code can use any in built random number generation function ...
user7467
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Hexagonal section numbers
Introduction
Let's draw some regular hexagons formed by hexagonal tiles, marking the vertices of the tiles with dots. Then we will count the number of dots.
...
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Longest Zero Sum Sub-array
Given an array of integers. Find out its longest sub-array (contiguous subsequence) whose sum is 0.
The sub-array for output may be an empty array.
Input
Input an array of integers.
Output
Output the ...
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votes
3
answers
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Is this an ordinal transform? [duplicate]
Related: What's my telephone number? which asks to calculate the terms of A000085, the number of possible ordinal transforms of length n.
Background
Ordinal transform is a transformation on an integer ...
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votes
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answers
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Maximum number of squares touched by a line segment
Consider a square grid on the plane, with unit spacing. A line segment of integer length \$L\$ is dropped at an arbitrary position with arbitrary orientation. The segment is said to "touch" ...
- 99.4k
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votes
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Is this a Permutation of 1..n
Input a non-empty array with \$n\$ positive integers. Test if the input array contains every integer in \$1\cdots n\$.
In case you prefer 0-indexed numbers, you may choose to input an array of non-...
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Give me odd, even, square, cube, prime and composite 3-digit numbers
Given a string which is guaranteed to be either odd, even, square, ...
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Binomial transform
Background
Binomial transform is a transform on a finite or infinite integer sequence, which yields another integer sequence. The binomial transform of a sequence \$\{a_n\}\$ is given by
$$s_n = \sum_{...
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Consecutive Distance Rating
We'll call the consecutive distance rating of an integer sequence the sum of the distances between consecutive integers. Consider 2 9 3 6 8 1.
...
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Collatz's ice cream cone factory
The Collatz sequence
Given a positive integer \$a_1\$, the Collatz sequence with starting value \$a_1\$ is defined as
\begin{equation}
a_{n+1} =
\begin{cases}
a_n/2 & \mathrm{if}\ a_n\ \mathrm{is}\...
- 99.4k
27
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Generate this number table
Given an integer \$1 < n < 10 \$ generate a table like below.
For \$n = 5\$,
1 2 3 4 5
2 2 3 4 5
3 3 3 4 5
4 4 4 4 5
5 5 5 5 5
For \$n = 8\$,
...
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iHateOddNumbers
Task
Given a non-negative number, check if it's odd or even. In case it's even, output that number. Otherwise, throw any exception/error that your language supports, and stop the program.
Example with ...
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Gödel numbering of a string
Background
Gödel numbers are a way of encoding any string with a unique positive integer, using prime factorisations:
First, each symbol in the alphabet is assigned a predetermined integer code.
Then, ...
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11
votes
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Calculate \$ \lfloor n \log_2(n) \rfloor \$, exactly
Given an integer \$ n \ge 2 \$, you need to calculate \$ \lfloor n \log_2(n) \rfloor \$, assuming all integers in your language are unbounded.
However, you may not ignore floating-point errors - for ...
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Dimensional Chess positions
Task
Any one of these two:
Determine if a given position (an ordered non-empty collection of integers in the range ‒8 to 8, or ‒7 to 7 if you want) is a valid Dimensional Chess position.
List all the ...
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votes
2
answers
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Gelatin integer metagolf
Gelatin is a worse version of Jelly. It is a tacit programming language that always takes a single integer argument and that has 7 (or maybe 16) commands.
Gelatin
Gelatin programs will always match ...
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